ORIGINAL: ceecrb1
I KNOW the source of the fuel leak. It is between the large nut for gripping the prop, and the bearings behind it.
I'd like to know more about this..
The engine has always done this but recently is a LOT worse.
At first I noticed the dirt inside the cowel after a months flying, now its after a days flying. I'm starting to wonder if the engine is heating up, expanding and loosing compression through there..... or something along those lines.
check back on the photo, you can see the bearings and a blue seal.. it comes from there.. but exactly which part of "there" I cannot say.
This cowel is REALLY dirty, like soaked, after yesterdays flying alone, which was about 5mins in the air and a total of 7-8ish mins run time on the ground.
I also noticed this with one of my 46XLS engines. I tried replacing the stock front bearing with a sealed bearing. The sealed bearing may or may not have reduced the fuel leak - I'm not sure - but the engine did not run any better with the sealed bearing.
As I understand it, the front seal is accomplished by the slip-fit clearance between the crank and the engine case, not by the front bearing. So a sealed front bearing is not necessary, however, if the clearance between crank diameter and case bore is too large a sealed front bearing might help.
I also understand there is a small weep hole between the crank area of the engine case to the front bearing. The purpose of the hole is to provide lubrication to the bearing(?). I have heard that if this hole is over sized there could be problems with air leaks and leaking fuel. For lack of a better idea, I believe this may be the problem with my engines. I have eliminated just about everything else.